Electric burglar-alarm



(No Modeh) 2 Sheets-Sheet 1.

1-1. 0. ROOME.

ELECTRIC BURGL-AR ALARM.

425 1599. Patented Mar.'7,1882.

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(No Model.) 2 Shet-Sheet 2.

H.OLROOMB. ELECTRIC BURGLAR ALARM.

No. 254,699. Patented Mar. 7,1882.

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HENRY O. ROOME, OF JERSEY CITY, NEW JERSEY.

ELECTRIC BURGLAR-ALARM.

SPECIFICATION forming part of Letters Patent No. 254,699, dated March 7, 1882.

Application filed March 7, 1881.

To all whom it may concern:

Be it known that I, HENRY U; RooME, of Jersey Oity,in the county of Hudson and State of New Jersey, have invented a certain new and useful Improvement in Electric Burglar- Alarms, of which the following is a specification.

My improvement relates to those electric burglar-alarms wherein an electriccurrent traverses buildings and other structures to be guarded, and connects them with a station or office where watchmen are kept.

The object of this improvement is to enable the watch men at the station or office at any desired time to more effectively ascertain whether all is right in the electric circuit at the structures to be guarded, and between the latter and the station or office.

My improvement consists in an electric burglar-alarm comprising a telephonic transmitter connected with the electric circuit at the structure to be guarded, a device for giving audible sounds located at the structure to be guarded, and a telephonic receiver in the station or office where watch is kept.

In the accompanying drawings, Figure 1 is a diagrammaticview of an electric burglar-alarm embodying my improvement; and Fig. 2 is a face view of a signaling and sounding instrument comprised in the same, its frame being partly broken away. 4

A designates a structure to be guarded, consisting, as here shown, of an electric covering for a safe.

B designates a telephonic transmittermounted on the inside of the structure or covering A, and here shown as consisting of a microphone composed of two buttons or plates of carbon, and a bar or piece of the same material loosely supported between them. From one end of this telephonic transmitter a wire, 0, extends to the ground. From the other end of the telephonic transmitter B a wire, F, extends to a resistance-coil, E, thence to a signaling and sounding instrument, T, which I will particularly describe hereinafter, both the resistance-coil and this instrument being here shown as mounted on the insideof the structure orcovering A. From this instrumentTthe wire F extends around the structure or covering A. As here shown, it extends down along the adjacent side of the covering or structure, thence (No model.)

across the bottom, and up the opposite side to a pairof contact-pieces, aand b, attached the one, a, to the covering or structure, and the other, I), to the door, and both continuing the electric circuit. From the contact-piece b the wire F extends downwardly, close to the inner edge of the door, nearly to the bottom of the door, thencelaterally nearly to the outer edge of the door, thence upward nearly to the upper edge of the door, thence laterally a short distance toward the inner edge of the door, thence downward nearly to the bottom edge of the door, thence laterally toward the inner edge of the door, thence upward nearly to the upper edge of the door, thence laterally nearly to the inner edge of the door, and thence downward to the upper hinge, c, of the door. From the hinge c the wire F extends up the adjacent side of the covering or structure, partly across the top, and thence out of the same. Thus a wirelined envelope or covering for a safe is formed. Leaving the structure the wire F passes to an instrument for indicating a change in the resistance in the circuit, (here shown as consisting of a galvanometer, H,) whence it extends to the battery I of the electric circuit, the primary wire of an induction-coil, K, and thence to the ground, the secondary wire of the induction-coil being connected with a telephonic receiver, L.

In connection with the galvanometer H is employed a local circuit, M, communicating with an electromagnetic bell or sounder, R, and a battery, S. It leads to a wire, N, connectin g with the needle n of the galvanometer, and branch wires 0 audP, connecting with stops 0 p, between which the needle may vibrate. The galvanometer-needle a is held by the battery 1 and resistance coil E about midway between the stops oand p. The deflection of the needle either way by any alteration in the resistance of the electric circuit, so as to cause it to touch either of the stops 0 or p, closes the local circuit 0 P M through the battery S and bell R, and thus effects the sound H, will be located in the oflice where watch is kept. By means of the telephonic transmitter and receiver sounds occasioned by any attempt to effect an entrance to the structure A, or to cut or vary the resistance in the electric circuit there, will be transmitted to the station or ofiice, and will serve to apprise the watchman of what is going on.

I will now turn again to the signaling and soundinginstrument. The wire F, after passing around the structure or covering A, leads to a binding-screw, Q, on the base-board of the said instrument. This instrument consists essentially of a train of gear-wheels, which may be made of metal, and are supported in a metal frame, which is shown in the drawings as partly broken away. They are driven by a convolute spring, which is combined with them through the agency of a ratchet-wheel and pawls, so that it may be wound without disturbing them,

and they comprise an escapement-wheel and detent to cause them to run slowly. A fan might be used instead of this escapement. The electric circuit extends by a wire, T, to the wire of an electro-magnct, T From this eleetro-magnet the circuit extends through a wire, T to a binding-screw, T and thence by the wire F to the resistance-coil E. From this resistance-coil it extends to the telephonic transmitter 13. This is the normal circuit through the instrument T, and while the structure to which they are applied is being guarded a current of electricity is flowing through the instrument from the battery I. The electromagnet '1 is provided with an armature, T arranged on one endof a lever, T which at the other end is impelled by a spring, T, to obtrude itself in the way of a pin, 0, carried by a gear-wheel, T, in the train of wheels comprised in the instrument.

On the same shaft as the wheel T is what I term a short-circuiting wheel, T which is made of metal and provided with a number of radial projections. When this wheel rotates its projections come in contact with what I term a short-'circuiting metallic spring-finger, T, which is attached to a block of insulating material mounted on the frame of the instrument T. A wire, T leads from this short-cireuiting finger to a binding-screw, T which has connected to it a ground-wire, T The binding-screw Q is connected to the metal frame of this instrument by a wire, T

The current produced by the battery I is insufficient to cause the electro-magnet T to attract its armature T Hence while the electric circuit in the structure to be guarded is in its normal condition the instrument T remains inoperative. If the watchman at the station or office desires to ascertain whether the circuit is all right, he, by means of a switch, X, cuts the battery I out of the circuit and throws a more powerful battery, W, into the circuit, and so increases the potential of the electric current passing through the circuit that the electro-magnet T attracts its armature T There- .upon the lever T releases the pin 6 on the Wheel T and the instrument T begins to run.

The battery W is only momentarily left in circuit and the batteryl out of the circuit. Hence as soon as the instrument starts,the electromagnet releases its armature and the lever resumes its former position, so as to be ready to engage with the pin 6 and stop the instrument again. The instrumentruns only long enough for the short-circuiting wheel T to make one rotation, and stops with the projections of this short-circuiting wheel out of contact with the short-circuiting finger T When the projections of the short-circuiting wheel during its rotation make contact with the short-circuiting finger the electric current from the battery I passes through the frame of the instrument T to the short-circuiting wheel and finger, thence to the binding-screw T and thence to the ground-wire T The electro-magnet T and the resistance coil E are thus short-circuited out of the electric circuit whenever any of the projections of the short-circuiting wheel make contact with the short-circuiting fin ger, but are in the electric circuit at other times. The radial projections of the short-circuiting wheel are so grouped that when they make contact with the short-circuiting finger they will cause a peculiar signal to be given to the watchman at the station or office.

As a number of structures will in practice he guarded from one station or office it is ad vantageous that each signaling and sounding instrument should be adapted to give a distinct and definite signal, so that in case a burglar should learn the signal which one of said instruments was adapted to give he would not thereby become apprised of the signals which the others were adapted to give.

Not only may the watchman by means of my invention obtain a signal from the structure to be guarded, but he may also through the telephonic transmitter and receiver ascertain whether the signaling-instrument is running. The sounding and signaling instrument preferably has an escapement which will develop a noise by which it can be distinguished, so that if a mechanism should be substituted for it by a burglar the watchman would readily become aware that it was not the signal and sounding instrument. This gives additional protection, for it is quite possible that a burglar might ascertain the signal which is transmitted by asignaling-instrument,and then give the signal with a telegraphic key introduced into the circuit; but itis very improbable that he could procure by chance a clock or other similar piece of mechanism the sound produced by the running of which would resemble that produced by the signaling and soundinginstrument having the peculiarly sounding escapement. Moreover, the telephonic transmitter and receiver should indicate by the sounds they transmit whether the signals are produced by making and breaking the electric circuit, as with a telegraphic key, or by merely changing the resistance, as in the above-described signaling and sounding instrument.

The advantage of combining an inductioncoil with the telephonic receiver is thatthe resistance of the said receiver is then out of the circuit, and a much less resistanceintroduced in lieu of it. This is advantageous in that the less the resistance which is in the circuit atthe station or oflice the less there need be in the circuit at the structure to be guarded. The burglar-alarm will be more accurate then and can be operated with less battery force. The induction-coil which I employ for this purpose difi'ers from the induction-coils commonly used for telephonic purposes in that the primary wire is made of greater resistance, because of the great resistance in the line with which it is connected, while in induction-coils as ordinarily used for telephonic purposes the priit mary wire is made of as possible.

What I claim as my invention, and desire to secure by Letters Patent, is-

In an electric burglar-alarm, a telephonic transmitter connected with the electric circuit at the structure to be guarded, a device for giving audible sounds located at the structure to be guarded, and a telephonic receiverin the station or office where watch is kept, substantially as specified.

HENRY O. ROOME.

Witnesses: EDWIN H. BROWN, H. F. NEWBURY.

little resistance as 

